An estimated 53.6 million women aged 35 to 49 are currently unable to conceive, prompting renewed concern about the scale of infertility worldwide.
A team from Chongqing Medical University examined health data from 204 countries spanning 1990 to 2023 to track changes in the “infertility burden” among women in this age range.
Their analysis found a steady increase over more than three decades, with rates climbing from about 6,001 cases per 100,000 women in 1990 to 6,907 per 100,000 in 2023.
Women up to age 49 are commonly counted in reproductive-age figures because some continue to menstruate and may still be biologically capable of pregnancy. Doctors note, however, that fertility drops significantly from the mid-30s and is typically very low by the late 40s.
According to findings published in The Lancet Obstetrics, Gynaecology, & Women’s Health, the sharpest projected rise was identified among women at the younger end of the 35-to-49 age group.
Researchers separated the women into three categories: ages 35 to 39, 40 to 44 and 45 to 49. Infertility was defined as the inability to achieve a clinical pregnancy after 12 months of regular, unprotected sex.
Using the data to model future trends, the study concluded that infertility is likely to increase in all three age groups, with the most pronounced rise expected among women aged 35 to 39.
That projection does not suggest women in their late 30s are more likely to be infertile than women in their 40s. Fertility still declines with age, largely because both the number and quality of eggs decrease over time.
There’s been a surge in women aged 35 to 49 who are struggling to conceive naturally
Instead, the finding suggests that the overall burden of infertility is growing fastest among women at the younger end of the ‘advanced maternal age’ group, likely reflecting the fact that more women are delaying motherhood into their late 30s as they focus on education and their careers.
But, by the time they feel ready to start a family, their fertility may already have begun to wane.
In the UK, the Office for National Statistics report on births for 2021 showed the average age of mothers in England and Wales was 30.9 years – the oldest on record.
This was part of a steady rise since 1973, when the average age of mothers was just 26.4 years.
The ONS figures also revealed that births among women over 40 were more than double those among teenagers. Just five decades ago, there were nine times as many teenage mothers as mothers over 40.
The authors of the new study also say obesity and stress may be having an influence on fertility.
Greater access to fertility treatment may also have increased both the number of women seeking help and the number of cases being diagnosed.
The other two age groups, 40 to 44 and 45 to 49, are also expected to see significant increases, bringing the total number of women affected by infertility to 79.6 million by 2036.
‘The subsequent increase from the late 1990s onward coincided with rising female participation in education and the labour force, leading to widespread delays in childbearing and a consequent rise in age-related infertility,’ wrote the study’s lead author, Yuanyuan Du.
‘A transient dip in observed infertility between 2006 and 2010 coincided with the global financial crisis, suggesting macroeconomic instability can alter reproductive timing.
‘However, this modest decline might reflect underdiagnosis due to economic barriers rather than a true reduction in prevalence.
‘The sustained rise in infertility since 2010 reflects delayed childbearing intersecting with obesity, stress and expanded ART access, which has improved case detection and extended reproductive windows.’
The infertility burden is not just apparent in poorer countries, with the data revealing a shift towards higher-income and more developed countries, probably reflecting later motherhood, population ageing and changing reproductive patterns.
However, women in lower-income settings still face major barriers, particularly because fertility testing and treatment are often harder to access.
In 2023, the most recent year analysed, East Asia had the highest regional burden, while Australasia had the lowest.
At country level, the Central African Republic had the highest reported burden, while Nepal had the lowest.
The researchers also noted that infertility in older reproductive-age women is not just a medical issue, but has psychological, social and economic effects.
These include distress, stigma, financial pressure, relationship strain and wider implications for ageing populations and workforce participation.
They argue that fertility care should be treated as a bigger public health priority, with better early detection, wider access to fertility services and policies tailored to different countries’ resources and needs.
